<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        a：link{
            color: red;
        }
        #a2:link{
            color: #2aabd2;
        }
        .a1:hover{
            color: #e4b9c0;
        }
        #a2:visited{
            color: #3e8f3e;
        }
    </style>
</head>
<body>

<a class="a1" href="#">001</a>
<a id="a2" href="#">002</a>
<a href="#">003</a>

</body>
</html>